Electrical codes require that busway tap-off devices be provided with an interlock which prevents installation or removal of the tap-off device from the busway electrical distribution system when the electrical disconnect device (switch or circuit breaker) within the tap-off device is in a CLOSED or ON condition. Typical bus to tap-off device interlocks of the prior art, such as illustrated in U.S. Pat. Nos. 3,339,038; 3,657,606 and 4,912,599, require a number of sliding members, linkage components and associated hardware that must be installed on the tap-off device enclosure. These extra interlock components and the time required to install them on the tap-off device enclosure add cost to the tap-off device. The interlock devices of the prior art can also require an extra step during installation and removal of the tap-off device.